Elevator systems which include an elevator control that controls one or more elevator cars servicing landings in a building typically include sensors of various types which provide information as to the status of operating conditions in the system. For example, door interlock and limit switches are typically provided to indicate when elevator car and hall doors are opened or closed and to indicate when the car is at its extreme lowermost or uppermost positions in the hoistway. Further, sensors are utilized which detect the load carried by the elevator car, the speed of the elevator car while traveling in the hoistway, when the elevator car is level at a landing, etc.
In addition to the foregoing sensors, switches are typically provided which, when actuated, affect the operation of the elevator car. For example, a door open switch is usually provided which, when actuated, opens the elevator and hall doors, at which time the elevator is prevented from moving. Also, a door photo switch and a safety edge are typically provided for each set of car doors which detect an obstruction preventing closure of the car and hall doors.
There are also various switches which are provided to stop the elevator or to allow inspection of the various mechanisms and cables.
At times, it may occur that a request for elevator service is issued yet the car is delayed in responding to such service request. This may be due to, for example, the detection of a fault condition, the detection of an unsafe or potentially unsafe condition, an obstruction in the car or hall doors, an actuation of the stop switch or the like. Such delays can be substantial in length, thereby resulting in inconvenience to users.
It would be useful to ascertain the cause(s) of a delay in responding to a request for service for various reasons. Chiefly, the source of a delay may identify a problem or potential problem with an elevator component. Alternatively, the cause of the delay may indicate the occurrence of abnormal conditions or activity external of the elevator system itself. Two examples of the latter are where a vandal has propped a stick or other obstruction between the elevator doors to prevent full closure of same or where seismic activity has caused the elevator to track incorrectly in the hoistway.
Knowledge of the cause of a delay event can also be informative of passenger habits and can lead to useful system adjustment information. For example, when a car is delayed an excessive number of times in responding to requests for service due to actuation of the door open button, it may be considered desirable to increase the door open time to allow entry and exit of more passengers without the need to actuate the door open button.
Thus, it can be seen that knowledge of the cause of a delay event can be useful for various reasons.
It is well proven to provide an indication of the operating status of an elevator system in "real time" in which information is provided concerning the current operating conditions. Such a "real time" indication, however, is generally of limited benefit since a technician must digest a great deal of information before useful conclusion can be drawn or he must, by chance, be present to note operating conditions during the occurrence of a fault or other event. Even in the latter case, the indication of the occurrence of an event may be short-lived, and hence the technician may be unable to obtain sufficient useful information to enable accurate diagnosis of the event cause.